In present day color photography the effect of color is obtained by three or more emulsions that are superimposed on a base with optical filters between the layers of emulsions. The base may be a transparent one such as a sheet of cellulose acetate, or it may be an opaque one such as a sheet of paper. Additional layers may be present such as antihalation layers, etc. Essentially the color is found in, generally, three separate emulsion layers. Each of the unexposed layers contains a light sensitive silver salt or silver halide and some form of coloring material that is originally substantially colorless but which during the processing of the film is converted to a color in proportion to the amount of silver in the silver image.
The nature of the photographic process is such that a color image cannot be any sharper than the original silver image which it replaces and very often the color image loses a certain amount of detail or resolution. Because of the nature of the color process itself, it is difficult to increase the resolution of the color images, but it has been found possible to increase the resolution of the overall image by making use of a thin silver image in conjunction with the color image in the top layer.
In certain technologies requiring high resolution developed film, such as in the aerial and microfiche/microfilm industries, color film did not provide the degree of resolution obtainable with black and white films. Therefore the use of color films in such industries was minimal at best. This was particularly so in color microfiche where fine reproduction of a color object was generally unobtainable.
In the microfiche/microfilm industry, standards such as Federal Microfiche Standards, Document No. PB 176 630, Committe on Scientific and Technical Information Federal Council for Science and Technology, 2nd edit., December 1965, dictated that the master film copy from a camera have a minimum resolution of 127 lines/mm at a background density of 0.9 to 1.2.
While such standards were achieved with black and white film, heretofore the art was incapable of achieving resolutions of about 127 lines/mm at 1.6:1 contrast for color film.
Similarly, aerial color photography resolution standards in industry, such as that found in Kodak Aerial Films and Photographic Plates, Publication M-61, Book No. 0-87985-037-X, Eastman Kodak Co. (1972) at p. D-28, sets forth the present commercial level for resolution in aerial color film as 100 lines/mm at a contrast of 1.6:1.
Now there is provided by the present invention, a developed color film from a camera, which exhibits a resolution in excess of 100 lines/mm at a contrast of 1.6:1, and also in excess of 127 lines/mm at a similar contrast. Thus the present developed color film now provides a commercially acceptable color microfiche/microfilm and an improved developed aerial photography film as well.
It is therefore a principal object of this invention to provide a developed color camera film having an improved resolution.
It is a further object of this invention to provide a developed film as aforesaid wherein the degree of resolution renders the film useful in both microfiche/microfilm as well as in aerial photography applications.
It is still a further object of this invention to provide a color film as aforesaid in which the color rendition is faithful to the colors in the photographed object.